Diversity of rhizobia isolated from an agricultural soil in Argentina based on carbon utilization and effects of herbicides on growth

Seventy-six rhizobial isolates belonging to four different genera were obtained from the root nodules of several legumes (Vicia sativa, Vicia faba, Medicago sativa, Melilotus sp., Glycine max and Lotus corniculatus). The action of five commonly used herbicides [2,4-dichlorophenoxyacetic acid (2,4-D), glyphosate (GF), dicamba, atrazine and metsulfuron-methyl] on the growth of rhizobial strains was assessed. Subsequently, GF and 2,4-D were tested in a minimum broth as C and energy sources for 20 tolerant strains. The ability of these strains to metabolize different carbon sources was studied in order to detect further differences among them. Tolerance of the bacteria to agrochemicals varied; 2,4-D and GF in solid medium inhibited and diminished growth, respectively, in slow-growing rhizobial strains. Among slow-growing strains we detected Bradyrhizobium sp. SJ140 that grew well in broth + GF as the sole C and energy source. No strain was found which could use 2,4-D as sole C source. The 20 strains studied exhibited different patterns of C sources utilization. Cluster analysis revealed three groups, corresponding to four genera of rhizobia: Rhizobium (group I), Sinorhizobium (group II) and Mesorhizobium–Bradyrhizobium (group III). On the basis of the results obtained on responses to herbicides and C sources utilization by the isolates investigated, it was possible to differentiate them at the level of strains. These results evidenced a considerable diversity in rhizobial populations that had not been previously described for Argentinean soils, and suggested a physiological potential to use natural and xenobiotic C sources.     

Chemometrical analysis of capillary electrophoresis casein fractions for predicting ripening times of milk mixture cheese

The effect of the ripening time on the proteolytic process in cheeses manufactured from mixtures of cow's and ewe's milk during a 167-day ripening period was monitored by capillary electrophoresis of the pH 4.6-insoluble fraction. Totals of 21 and 16 peaks were recognized and matched in the electropherograms obtained with a fused-silica capillary and a neutral capillary (hydrophilically coated), respectively. These peaks corresponded to intact bovine and ovine caseins and their hydrolysis products (e.g., alpha(s1)-casein, gamma-caseins). In 167-day-old cheeses, bovine alpha(s0)-casein (alpha(s1)-casein 9P) had been completely degraded and 6% of the residual bovine alpha(s1)-casein remained intact. Breakdown of the beta-casein fraction was lower than that of the alpha(s)-casein fraction. Finally, partial least-squares regression and principal component regression were used to predict the ripening time in cheeses. The root-mean-square errors in prediction by cross-validation were <7.8 days in all cases.     

Effect of high-intensity pulsed electric fields processing and conventional heat treatment on orange-carrot juice carotenoids

Liquid chromatography (LC) was the method of choice for quantification of carotenoids (including geometrical isomers) to evaluate the effects of high-intensity pulsed electric field (HIPEF), a nonthermal preservation method, with different parameters (electric field intensities and treatment times), on an orange-carrot juice mixture (80:20, v/v). In parallel, a conventional heat treatment (98 degrees C, 21 s) was applied to the juice. HIPEF processing generally caused a significant increase in the concentrations of the carotenoids identified as treatment time increased. HIPEF treatment at 25 and 30 kV/cm provided a vitamin A concentration higher than that found in the pasteurized juice.     

Furosine as indicator of maillard reaction in jams and fruit-based infant foods

To investigate the presence of furosine in commercial samples of jams and fruit-based infant foods a simple method by ion-pair reversed-phase liquid chromatography is described. The yield of furosine during the hydrolysis with hydrochloric acid was optimized. The reproducibility in the repeatability and recovery of the method, expressed in relative standard deviation percentages, proved to be in the ranges of 4.1-8.3% and 1.0-4.4%, respectively. The recovery percentages of furosine varied between 86.7 and 95.3%. The obtained results support the suitability of the method. Furosine was detected in all studied samples. Although a high variability in the content of furosine was noticed, in general terms, the lowest levels of furosine were observed in samples of fruit-based infant foods and the highest were observed in jams of more than 60% sugar. These results could be due to different heat treatment, storage conditions, and/or differences in the values of water activity (a(w)) and amounts of sugar. The results obtained in the present paper point out the usefulness of furosine as an indicator of Maillard reaction for jams and fruit-based infant foods.     

Using the Landfarming Technique to Remediate Soils Contaminated with Hexachlorocyclohexane Isomers

The purpose of the present study is to simulate concentrations of ozone and its precursors (NO and NO₂) in an area under the influence of the Candiota coal-fired power station by applying numerical models. The photochemical simulations were conducted during two distinct periods: in summer (from 24 to 26 January 2003) and in winter (from 10 to 12 August, 2004). With the RAMS atmospheric model (Regional Atmospheric Modelling System) we obtained meteorological fields to initialize the CIT photochemical model. The emission data were based on the AP-42 and only compounds emitted during coal burning were considered. The simulated results revealed high ozone levels in warmer periods, being related to high temperatures and water vapor concentrations. The simulated concentrations are located far from the emitting source, favoring reaction and mixing time between precursors to form ozone. Simulated winds of small intensity favored ozone transport, mixing and accumulation in areas far from the emitting source.     

Genetic parameter estimation and gene association analyses for meat quality traits in open-air free-range Iberian pigs

Meat quality of Iberian pigs is defined by the combination of their genetic characteristics and the particular production system. To carry out a genetic analysis of the main meat quality traits, we estimated their heritabilities, genetic correlations and the association effects of 32 selected SNPs of 12 candidate genes. A total of ten traits were measured in longissimus dorsi samples from 1,199 Iberian pigs fattened in the traditional free-range system: water holding capacity (thawing, cooking and centrifuge force water losses), instrumental colour (lightness L*, redness a* and yellowness b*), myoglobin content, shear force on cooked meat, and shear force and maximum compression force on dry-cured loin. Estimated heritability values were low to moderate (0.01 to 0.43) being the lowest for L* and the highest for cooking loss. Strong genetic correlations between water holding capacity traits (0.93 to 0.96) and between myoglobin content and a* (0.94) were observed. The association analyses revealed 19 SNPs significantly associated with different traits. Consistent and strong effects were observed between PRKAG3 SNPs (rs319678464G > C and rs330427832C > T), MYH3_rs81437544T > C, CASP3_rs319658214G > T and CTSL_rs332171512A > G and water losses. Also for CAPN1_rs81358667G > A and CASP3_rs319658214G > T and shear force. The SNPs mapping on PRKAG3 showed the highest effects on Minolta colour traits. Genotyping of these SNPs could be useful for the selection of Iberian young boars with similar estimated breeding values for productive traits.     

Effects of different bronopol treatments on final survival rates in the artificial incubation of crayfish eggs (Pacifastacus leniusculus,Astacidae)

Two experiments were conducted on the effects of bronopol in the artificial incubation of crayfish eggs (Pacifastacus leniusculus) with the aim to search an alternative to formaldehyde. In the first experiment, 50, 250, 500 and 1000 ppm bronopol and 3000 ppm formaldehyde (control) in periodical administrations were tested on a density of 6.6 eggs cm^?2. After 44 days of incubation, the highest survival was obtained with 1000 ppm bronopol (81.9% to stage 2 juvenile, with no significant difference from formaldehyde), whereas lower bronopol concentrations resulted in significantly lower survival. In the second experiment, 1000, 3000 and 5000 ppm bronopol and 3000 ppm formaldehyde (control) administered for 15 min every second day were tested on eggs at a density of 20 eggs cm^?2. After 78 days of incubation, bronopol at 3000 ppm allowed for a stage 2 juvenile survival rate of 65.0% (with no significant difference from formaldehyde), whereas significantly lower survival was obtained with 1000 ppm or 5000 ppm. This study shows that bronopol may constitute an alternative to formaldehyde in the artificial incubation of crayfish eggs. A concentration of 3000 ppm administered for 15 min every second day may be adequate even on long incubations at high densities (at least 20 eggs cm^?2, one complete layer).     

Effect of chlorimuron-ethyl on Bradyrhizobium japonicum and its symbiosis with soybean

Possible side-effects of the acetolactate synthase (ALS)-inhibiting herbicide chlorimuron-ethyl on Bradyrhizobium japonicum (Kirchner & Jordan) in pure culture and on inoculated soybean plants growing under controlled conditions were investigated. Growth of B japonicum strain E109 was not affected by this herbicide even when exposed to concentrations 150 times higher than recommended field doses. However, nodulation of soybean plants treated 5 days after emergence with chlorimuron-ethyl at standard application rates was impaired: a 38% decrease in the number of nodules per plant was observed four weeks after treatment. Despite nodule number decrease, no changes in shoot nitrogen content could be detected. Total fresh biomass was diminished by 25% in herbicide-treated plants. Leghemoglobin content in nodules did not vary; nevertheless total nodule protein was diminished by 40% in the herbicide-treated group. ALS activity in different soybean tissues and their relative sensitivity to chlorimuron-ethyl were also investigated. Roots and bacteroids had the greatest specific ALS activities. On a fresh weight basis, the bacteroid fraction displayed the highest ALS activity and was also the most tolerant to in vitro chlorimuron addition: 72% of its activity was retained after including 10 microM chlorimuron-ethyl in the reaction mixture. These results indicate that standard application rates of chlorimuron-ethyl will have limited incidence on B japonicum survival, and effects on nodulation may have little long-term consequences on soybean nitrogen fixation potential. The differences found among soybean tissues not only in intrinsic ALS activity but also in their relative sensitivity to this herbicide suggests that, in leguminous plants living in symbiosis with rhizobia, nodules may contribute to an enhanced tolerance to ALS inhibitors.     

Assessment of relevant factors and relationships concerning human dermal exposure to pesticides in greenhouse applications

Principal component analysis (PCA) was applied to the gas chromatographic data obtained from 23 different greenhouse trials. This was used to establish which factors, including application technique (very small, small, medium and large drop-size), crop characteristics (short/tall, thin/dense) and pattern application of the operator (walking towards or away from the treated area) are relevant to the dermal exposure levels of greenhouse applicators. The results showed that the highest exposure by pesticides during field applications in greenhouses, in the climatic conditions and in the crop conditions typical of a southern European country, occurs on the lower legs and front thighs of the applicators. Similar results were obtained by hierarchical cluster analysis (HCA). Drop-size seems to be very important in determining total exposure, while height and density of crops have little influence on total exposure under the conditions of the present study. No pesticide type is a major factor in total exposure. The application of multiple regression analysis (MRA) allowed assessment of the relationships between the pesticide exposure of the less affected parts of the body with the most affected parts.